Generation and Characterization of High Heat-Flux Plasma-Flow for Divertor Simulation Studies using a Large Tandem Mirror Device

Full text: This paper describes the results of high heat and particle flux generation performed at an end-mirror exit of a large tandem mirror device for divertor simulation studies. In a large tandem mirror device GAMMA 10 of Plasma Research Center, University of Tsukuba, a number of plasma production/heating systems with the same scale of fusion devices have been equipped and high-temperature plasmas have been produced. As a future research plan, making use of the advantage of open magnetic field configuration, we are planning to start a study of divertor simulation under the closely resemble to actual fusion plasma circumstances and to directly contribute the solution for realizing the divertor in ITER. For the above purpose, development of a new axi-symmetric divertor configuration like a toroidal divertor and high heat-flux experiment in the end-mirror region are started. In typical hot-ion-mode plasmas (ne ∼ 2 x 1018 cm-3, Ti ∼ 5 keV in the central-cell), the heat-flux density of 0.6 MW/m2 and the particle-flux density of 1022 H/s·m2 were achieved in the case of only ICRF heating. Furthermore, overlaying of 300 kW ECH to the plasma attained a peak value of the net heat-flux up to 8 MW/m2 on axis. The net heat-flux continues to increase with the ECH power and is expected to be achieved up to the level of 10 MW/m2 within the available power of ECH, which almost corresponds to the heat load of the divertor plate of ITER. Above results give a clear prospect of generating the required heat-flux density for divertor studies by building up the plasma heating systems to the end-mirror cell. Detailed characteristics of obtained heat and particle flux are also discussed. (author)